From the Guidelines
The palatine tonsil is the lymphatic tissue that lies between the palatoglossal fold and the palatopharyngeal fold. This lymphoid tissue is part of Waldeyer's ring, a circular arrangement of lymphatic tissue in the pharynx that also includes the lingual tonsil, pharyngeal tonsil (adenoids), and tubal tonsils. The palatine tonsils serve an important immunological function as they are strategically positioned at the entrance of the respiratory and digestive tracts, where they can sample antigens and initiate immune responses against potential pathogens, as described in the clinical practice guideline: tonsillectomy in children (update) 1.
Key Characteristics of Palatine Tonsils
- They are covered by stratified squamous epithelium and contain numerous crypts that increase their surface area, enhancing their ability to capture and process foreign material.
- The palatine tonsils are most prominent during childhood, between the ages of 3 and 10 years, and tend to involute with age as the immune system matures, as noted in the executive summary of the clinical practice guideline: tonsillectomy in children (update) 1.
- The epithelium of the tonsils is cryptic and reticulated and contains a system of specialized channels lined by “M” cells, which take up antigens into vesicles and transport them to the extrafollicular region or the lymphoid follicles 1.
Immunological Function
The palatine tonsils produce all 5 immunoglobulin (Ig) isotypes, with IgA being arguably the most important product of the tonsillar immune system, playing a critical role in the mucosal immune system of the upper airway 1. The tonsils are capable of initiating immune responses against antigens entering the body through the mouth or nose, making them a crucial part of the immune system, especially during childhood 1.
From the Research
Lymphatic Tissue Location
The lymphatic tissue located between the palatoglossal fold and palatopharyngeal fold is part of the Waldeyer's ring, which includes:
- Palatine tonsils
- Nasopharyngeal tonsil (adenoid)
- Lingual tonsil
- Tubal tonsils
- Lateral pharyngeal bands
Composition of Waldeyer's Ring
Waldeyer's ring is composed of mucosa-associated lymphoid tissue (MALT) and is located at the gateway of the respiratory and alimentary tract 2. The palatine tonsils, which are part of this ring, are compact yet physiologically complex mucosa-associated lymphoid tissues that function in exogenous antigen sampling and stimulation of immune responses 3.
Specific Lymphatic Tissue
The specific lymphatic tissue between the palatoglossal and palatopharyngeal folds is the palatine tonsils, which are the largest tonsil in Waldeyer's lymphatic ring 4. The palatine tonsils possess lymphatics in the parafollicular area, in the connective tissue septa, and in the capsules, but not in the subepithelial area between the follicles and the follicle-associated epithelia or within the follicles 5.
Function of Palatine Tonsils
The palatine tonsils are considered the first line of defense against exogenous aggressors, and the generation of B cells in the germinal centers of the tonsil is one of the most essential tonsillar functions 2. However, the adenoids, not the palatine tonsils, are the main reservoir for potential pathogens leading to acute otitis media (AOM) and secretory otitis media (SOM) 6.